Description: The Aquatic Toxicology Facilities and Services Core provides facilities and expertise to support the use of aquatic animal models in environmental health research. The central facility is the Food Toxicology and Nutrition Laboratory, which houses approximately 475 large tanks for trout, smaller aquaria for medaka and zebrafish and associated facilities. It includes a rainbow trout hatchery, diet preparation rooms, laboratories and offices. The hatchery is configured to rear brood stock under southern hemisphere and northern hemisphere photoperiods, producing both fall and spring spawners. The trout tanks are supplied with constant temperature (13 degrees Centigrade) well water, which is degassed to avoid problems caused by nitrogen supersaturation. An electronic control system monitors environmental variables in the laboratory and tanks. Much of the research using this Core has involved long-term carcinogenesis experiments using trout and, to a lesser extent, zebrafish. Shorter term metabolism and molecular biology experiments have also been supported by this facility. Core personnel are also involved in the training of graduate students and postdoctoral researchers in the areas of fish husbandry and maintenance, carcinogen handling and administration, fish dissection and necropsy, and histopathology. In December 1998, the facility experienced a large fish kill, with the loss of 98 percent of the fish stock; at least seven experiments were lost, including one large molecular dosimetry experiment with indole-3-carbinol and dibenzo[a,l]pyrene. Infectious disease and oxygen deprivation have been ruled out, but the exact cause has not yet been identified. A chemical etiology is suspected. During the current funding period, the Core supported rainbow trout tumor studies by three major users (Drs. Bailey, Hendricks, and Williams). It also supplied fish and materials to eight other investigators at OSU and provided assistance to 14 graduate students and 3 postdoctoral researchers; most of the students and postdoctorals were in the laboratories of the three principal users. Since the last competitive review work supported by the Core has resulted in approximately 67 papers published in respected peer-reviewed journals in carcinogenesis and toxicology. Use of the Core is prioritized based on Center affiliation. Future plans include additional carcinogenesis studies (another ED 0.1 percent study with another carcinogen) plus experiments on stress proteins and P450s, as well as further development of zebrafish as a model, in collaboration with other centers.